Method of coating articles



July 17, 1934. n. K. LEE

-IETHOD OF COATING ARTICLES Filed Nov. 22, 195o L Y RK. M mR N WE m Wmv. on

i Patented July 11, 1934 METHOD F COATING ARTICLES Roger K. Lee, Highland Park, Mich., assignor to Chrysler Corporation, Detroit, Mich.. a corporation of Delaware Application November 22, 1930, Serial No. 497,527

3 Claims. (Cl. 21S- 47) The main objects of this invention are to provide an improved apparatus for heating metal cores, or other articles having a metal part, during an immersion coating treatment; to provide apparatus of this kind which heats the articles or cores internally; to provide apparatus for supplying heat to a metal article while it is immersed in a coating solution without the aid of energy conducting attachments of a physical nature so as to obviate covering of portions of the article and to permit formation of a continuous layer of coating material on all the exposed surfaces of the article; and to provide 'electrical apparatus for inductively heating metal articles while they 1| are immersed in a coating of treating solution so.

as to obviate heating of the'entire solution of a bath and to concentrate the application of heat to those parts of the solution which are in intl--l mate contact, and those portions in close proximigo ty to the article.

Further objects of the invention are to provide an improved method for coating articles which is particularly adapted for forming coatings of rubber thereon; and to provide an improved method 2; of this kind by which rubber is simultaneously deposited'and heat cured on a metal article. An illustrative embodiment of theinvention is shown in the accompanying drawing, in which:

Fig. 1 is a perspective view of a steering wheel so illustrating one example of an article which may be economically coated with my improved method. Fig. 2 is a sectional view taken on the line 2-2 of Fig. 1.

Fig. 3 is a plan view of coating apparatus embodying my invention. Fig. 4 is a central vertical section taken on the line 4-4 of Fig. 3.

In Figs. 3 and 4 is illustrated one example of a coating apparatus which may be used in coat- 4Q ing articles in accordance with my improved method. This apparatus includes a receptacle or tank 1 which is formed of glass, crockery, porcelain or other material having a low magnetic permeability. The tank 1 is received centrally in g a helical coil 2 which is preferably connected in a comparatively low voltage, low frequency alternating circuit, not shown.

The coil 2 may be supplied with interrupted direct current instead of the alternating current if desired. A circuit having a voltage of from 110 to 300 volts and a frequency of 180 cycles per` second will operate the apparatus successfully. A magnetic ileld havin! suitable characteristics maybecreatedinanydesircdmannerandtheapparahbywhichtllmddideveloped,

is preferably constructed so as to produce lines of `force which are conveniently intercepted by all portions of a particular article on which the coating is formed.

An article, such as a steering wheel 3, is supe0 ported in the tank 1 upon a T-shaped rod 4 having va head portion 5 which is received upon the upper edge 6 of the tank. The tank is lled with a coating composition of a liquid, plastic or slightly mobie nature. Thermoplastic coatings oi various 05 kinds such as bakelite, resinous compounds and rubber may be formed on the article by providing p a mobile composltion of these substances in the tank i.

The above apparatus and my improved method is particularly adapted for forming a rubber coating 'I on a steering Wheel as illustrated in Fig. 2 or on other articles. The rubber bath may be formed by dissolving or suspending rubber in a suitable liquid or volatile solvent such as gasoline.

In operation, when the circuit which includes the coil 2 is closed, a magnetic fieldv is created which passes through the tank 1 and its contents.

The lines of force of the magnetic field are ingo tercepted by, and concentrated around the metal core or article 3 which preferably includes iron having a high degree of magnetic permeability and which is located centrally of the field. The article is inductively heated by the magnetic iield of the core to a desired temperature by varying the characteristics of the circuit in which the coil 2 is included. The heat which is generated internally inthe core vaporizes the solvent of the composition with which the core contacts and causes a layer of rubber of substantial thickness to be built up upon the core. As heat is suppliedr to the core without the aid o! contacting physical heat conducting means, substantially the entire outer surface of the core is exposed to the coat- 95 ing composition, therefore the resulting coating Vis continuous. 'I'he rubber is simultaneously deposited on the core and heat cured while the core is immersed in the coating composition. The heating curing action may be carried to any deslred degree by controlling the temperature of the core and it may be completed if necessary v by subjecting the coated core to a subsequent heat treatment after it is removed from 'the tank 1. 105

The level of vthe coating bath 'is preferably maintained considerably below the uppermost convolution of the coil 2, as shown in Fig. 4, so astoprovidearangeinthereceptacleinwhich thesteeringwheeimaybeindwvelyheatedllo by the coil while it is out of the bath. The Wheel may be successively dipped into the bath and lifted into the space above the bath, Within the magnetic eld, so as to alternately deposit rubber on the exterior of the wheel and cure the successive deposit. Due to the absence of the curing effect of the coating composition when the Wheel is in the space above the bath, a temperature of a higher degree is developed for the curing treatment.

In practice, a substantially uniform concentration of the coating bath is maintained by continuously feeding a. supply or" the coating composition into the tank through an inlet pipe 8 and removing from the tank a portion of the composition which has been acted upon by heat through the outlet pipe 9. Circulation of the coating composition through the tank in this manner may be employed to agitate the coating bath and to retain the bulk of the bath at a predetermined substantially lotv temperature so as to prevent excessive vaporization of the solvent or liquid phase from the bulk of the bath by the heat which is applied thereto during inductive heating of the article.

Although but one specific embodiment of this invention has herein been shown and described, it will be understood that various changes in the size, shape and arrangement of parts may be made Without departing from the spirit of my invention and it is not my intention to limit its scope other than by the terms of the appended claims.

What I claim is:

The method or' forming a thermo-plastic coating on an article having a metallic component which consists in creating a. magnetic field throughout a coating bath and in the space above the level thereof, and alternately dipping said article in said bath and holding the same in the magnetic eld above the bath so as to inductively heat the article alternately in the bath and in atmosphere.

2. The method of forming a rubber coating on a metal article from a bath comprising a liquid coating composition including a volatile vehicle and a curable rubber composition which consists in continuously feeding said coating composition into the lower extremity of a receptacle comprising non-magnetic material and removing some of said coating composition from said receptacle at a higher elevation so as to maintain the rubber concentration of said bath and the level thereof substantially uniform, creating a magnetic eld throughout said bath and in the space above the level thereof, and alternately placing said article in said bath and in the magnetic eld above the latter so as to alternately heat said article in said bath for depositing said rubber composition thereon and heat cure the latter in the atmosphere.

3. The method of forming a coating on an article having a metallic component which consists in creating a magnetic eld throughout a coating bath and in a space adjacent thereto, and alternately dipping said article m said bath and holding the same in the magnetic field of said space adjacent said bath so as to inductively heat the article ,alternately in the bath and in atmosphere.

ROGER E12. LEE. 

